Around 12:40 into the episode, when Princess Carolyn and Vincent Adultman argue in the restaurant, the plate of steak in front of the walrus appears and vanishes a couple times.
At around 9:00 Bojack puts down the copy of "Untitled Project by the Coen Brothers" on the desk only for it to completely disappear during the next camera cut.
Lenny Turteltaub states that Secretariat was "dead by 27". While it's technically true that Secretariat didn't live to 28, the horse was euthanized at age 19.